Expander device



April 22, 1952 A. R. HEDBERG 2,594,164

April 22, 1952 A. R. HEDBERG 2,s94,164

EXPANDER DEVICE Filed Nov. 29, 1946 4 Sheets-Sheet 2 Y IIIIIIIIIN 32 April 22, 1952 A. R. HEDBERG 2,594,164

EXPANDER DEVICE Filed Nov. 29, 1946 4 Sheets-Sheet 3 April 22, 1952 A. R. HEDBERG 2,594,l64

EXPANDER DEVICE Filed Nov. 29, 1946 4 Sheets-Sheet 4 piston walls.

Patentecl Apr. 22, 1952 UNITED STATES PATENT OFF-ICE EXPANDER DEVICE Aldrich R. Hedberg, Cleveland, Ohio, assignor by Vdirect and mesne assignments, of one-hall' to Apueation November 29, 1946, Serial No. 713,151

i (cl. zei-1) vices in general, and relates expanders thereof.

There are many types of mechanical devices in which reciprocating members operate relative to statonary members and in which a pressure differential exists along various portions of the members. Pressure pumps'make up the mass bulk of these devices but there are many instances in which a reciprocating shaft extends from a relatively low pressure area into a relatively high pressure area. In these devices, the sealing of the differential pressure existing between a low pressure area and a high pressure area is very often an acute problem. In some types of devices, only a moderately eflicient seal is required, whereas in other types of devices, a very tight seal is required.

, There are, of course, many different types of sealing and packing devices used to cooperate with such devices to form piston packing and pressure gland packing, but the present invention is described and illustrated with the type generally referred to as a cup and fiange packing. These packings may be made of leather or other suitable flexible material, and are well known to the industry.

In using these packingsyspecific problems must be met in order to keep the packing Operating more particularly to efiiciently. The cup type packings are generally 1 carried by the movable piston, in the case of the piston type seal, and are movable relative to the However, when used to seal about a moving rod. such for example as a piston rod, the packing is generally held stationary with the packing gland, and the piston rod or other moving shaft moves relative thereto.

In devices in which the differential pressure is always substantially constant, and above a predetermined value, there is very little problem in keeping these packings tight, because the pressure upon the packing will always hold the packing tightly against the adjacent member and will cause the packing to continue to press, tightly against the adjacent member as wear progresses. However, a different problem exists when the pressure repeatedly fluctuates from a low differential pressure to a high differential pressure. In this type of operation, auxiliary expander devces must .be used in connection with the flange of the packing in order to hold the flange tightly against the adjacent member during the build up of differential pressure. If these expander devices' are not used to hold the flange tightly in place, the fiuid pressure as it is built up will be 2 able to force its Way between the packing flange and the adjacent member, because there is no force holding the packing member tightly against the adjacent member. Once this condition exists, no amount of pressure will cause the packing fiange to seat tightly against the adjacent member because the fluid pressure on both sides of the packing flange isequal. Therefore, the packing flange remains free to move away from the adjacent member just as if it'were under only atmospheric pressure.

Expander devices used in connection with packing flanges to hold the packing fianges tightly 4 against the adjacent member, have become fairly devices generally fit against the flange of the packing'and the'notched and bent edges contact the flange of the packing and press the flange tightly into contact with the adjacent member to be sealed. This type of device is quite successful and is widely used today. However, the outstanding drawback to this type of expander device is its expense. This is especially true for the large piston sizes. When making the larger piston size expander device by this latter method, it is quite often necessary to fabricate the expander from several pieces of smaller material. This is required, because the spring material generally used is spring steel or spring bronze, and these materials are available only in limited widths. Therefore, these materials are obtained in their widest width, and whenever an expander device is required of -a greater diameter than the maximum available width, several pieces of the material are fabricated together in order to make a complete device. V

Further. the devices in which packing expanders are required, are not generally standardized in size throughout the industry. Accordingly, in order to make expander devices of this letter type, it is often necessary to make a complete set of dies to manufacture only a relatively few expanders. In fact, as often happens, the cost of the dies for making expanders of a given size far exceeds the value of the total number of complete expanders. required, even when the size 3 is small enough to be made from one single piece of stock material of the'dies.

Accordingly, an object of my invention is to provide a universally flexible expander device capable of being flexedI-into an arcuate'structure.

Another object of4 my invention is to provide a strip member expander device capabley of being flexed into 'an arcuate structure of any suitable diameter.

Another object of my invention is to cleave and bend a strip of spring metal in a manner capable of providingr universal flexibility in said strip.

invention may be had -by referring to the follow- Figure Lis-a top plan view of the formed strip.

ofuF-igurefz as itappears 'arcuately fiexed; 4

yligurveo -is across-sectional view along the lines 5-15 of Figure 4; i I k I Figure. 6 Vis a. view similar :to Figure 4 'witn a forming ring in conjunction therewith;

FigureV 7 a cross-sectional view 'along the lines 'Ii-'I -of Figure 6;

Figure 8 is a view similar fication of my -inventio'n-;

toFigure 1 of a modi- Figure9 is 'fa view similar 'to 'Figure 4 of the.

modi-ed form; i

:Figure -10 is a topkplan/view of a formed strip made in accordance W-ith'the mo dified Lform of my Figurel 1-1 is 'a 'sectional view of the modified form;I H

Figure "1'2 is a -cross-sectional viewof apiston packing -employing my improved ekpander device and f'orming ring held in .place by a. pressurey plate; i

Figure 13 na view similar teflfihejnigme 1'2' with a n'otch provided vin thep-ressure .plate to accom- I modate myv improved 'expanding device and forming ring:

Figure 14 isv-iew of my -improvedexpanderl device a's 'directly -positioned by the pressure plate;

'Figure 15 is a modified bending form of -my improved'fexpander device;

-Figure '16 :is 'another modified ben-d-i-ng form of m'yimprovedexpander device;

Figure -17 Vis 'a view vsimilar to Figure -1, with bend lines indicated therealong for forming the blank. for 'use with Va shaf-t seal- -flange packing;

:Figure 1'8 is a ltopplan view-'of the modified form of my invention;

Figure 19,-is an end view =of Figure 18-;

'Figure -20 is'a top plan. view of theinvention of Figure -18 flexed about Ca circum-ference in suitable form for'use 'with a shaft Seal vflange pack- -l3'igu're'2-2 is a view 'similar to 'Figure 2-1 Vill-us-- V trating the pressure plate with a notch therein to Other objects and a fuller understanding of 'myaccommodate the flange packing and m'y ini-4 proved expander device;

Figure 23 is a cross-sectional View of a'shaft packing fiange illustrating the use of my improved expander device held directly in place by the pressure plate;

Figure 2,4 is amodified bending form of my improved packing expander in use with a sh'aft seal iange.

With reference to the Figure 1 of the drawings,

I 'illustrate the first step in producing an expander device in accordance with the provisions ing description and claims taken in conjunction of myinvention. In the Figure 1, a blank 20 is producedfrom a'l'strip'of spring metal of the desired width having a first side edge I and a second'side edge [2. 'I'he blank 20 is formed to provide a'first series' of clear/'ages ES extending from hfl said4 first -side edge Il inwardly of the blank 20 towards the side edge i2. A second series of cleavages !9 extend from1 the sideedge |2 inwardly of vthe; blank ftoward the side edge II. The'cleava'g'es IB and is arerlongitudinally staggeredas illustrated in the Figure 1 tor'etai'n the blank as a one-'piece structure. That is, the two series'of cle'ava'ge's are offset in order that theywill not produce adivisional cut acrossy the blank 20.

In the preferred embodi'ment'of my invention,

for an expander "to 'cooperate with the 'outwardly ex-tending,v or piston type, packi'ng, 'the series of cleavages vI ii are .preferably in the form 'of taper'ed slots, whereas the series of cleavages IQ are simple division cuts over a portion of their length, and are slotted, as by slots 21, over the remainder of their length in order to relieve the 'stress concentration which a simple divi'si'onal 'cut Would produce by ending directly 'in a. 'solid 'wa-ll "of metal. Thus, in the Figure 1, I have 'illustrate'd each cleavage of the series 29 as comprising a composite of a simple divisional cut 22 'and a slot 2 'I'he slot22, however, could very well be continued the full length of the cleavage 19 with identical results insofar as performance 'is concerned. f i

I have described. my vinve'n't'i'on only by the steps of producing the preferred 'e'inbo'diment. vFundamentally, the preferred 'e'znbodi-v ment of the black 20 should compri'se a leg member 23 -.and a leg 'member 24 at oppositely disposed sides of'the blank 20, 'and connected together by cross legs 25 and 26. That is, each leg member 2.3 has two cross members'ZS and 25 extending -therefromj VThe cross 'member 25 extends to a first leg v'24, and Vthe cross Vmember "26 extends to. a second leg 24 adiac'ent to the first leg. Likewise, eaohleg member '2'4 has'two cross members 25 and 26, one leg extending'to afirs't leg- -23 and the other cross 'member 'extending 'to a second .leg 23 adj'acent to the firs't ll'e'g.

As -is well known, al sheet of material rhaving a relatively large width and a'thin cross-section is notflexible in its own plane, and anyIforcefi-n its o-wnplane will ter-id to -buckle and t'ear the 'material. I-Iowever, this same sheet. of material'may be: 'q'uite' easily flexed laterally about its thin dimension. VIn other Words, itmig'ht be said 'that a relatively thin piece of material maybe readily flexed in any direction except its own plane.

As thus 'far described, the blank 20 'illlustrated in the Figure, l remains lin its own original plane. Any *attempt to curve the blank .20 in its own plane Would be decidedly limited because of the described buckling and tearing tendency which would tak-eplace fin the legs 23 and -24 kbetween the ends of the slots l8 and the side edge'l2,

and the end of the slots 21 and the side edge Il.

I-Iowever, I have found that'the blank may be bent about the bend line 2'1 and 28 as illustrated in the Figure 1, and will produce a strip expander member 10 having the cross-sectional configuration illustrated in the Figure 3, and will thenl be readily fiexible. This apparent phenomena will be readily understood by reference to the Figure 4 of the drawing. In the Figure 4, the strip expander member 10 has been arcuately flexed about a circular circumference. This fiexing is brought about by moving the narrow leg members 24 toward one another and reducing the width of the slots 18 at the .side edge 11. In moving the narrow legs 24 toward one another, a flexing stress was produced in the wide leg members 23. However, the wide leg members 23 are disposed at an angle to the angle of the cross leg members and 26, and therefore tend to bencl about the thin dimension of the material from which it is made rather than in the plane of the material. Accordingly, each individual wide leg member 23 is caused to .flex slightly about its thin dimension to allow the cross legsy bers 15 and 13, and the bottom land portion I'I,

are proportioned as illustrated in the Figures 3 and 5 only for the purpose of illustrating the invention. The fundamental requirement being, that at least the solid bridging portion of the legs 15, orthe solid bridging portion of the' legs 10, (and preferably both when small diameter flexing is required), along the side edges 11 and 12, be disposed at an angle to the plane of the bottom land portion 11. Thus, the cross-sectional configuration of the expander strip member 10 may be considered as being substantially U-shaped.

In the Figures 6 and 7 of the drawings, I illustrate the curved expander strip 10 as being secured to a ring member 13. The ring member 13 is used for the purpose of accurately positioning the strip member 10 and permits the strip member 10 to be placed in position relative to the packing flange without auxiliary spacing and positioning means.

Although I have illustrated the ring member 13 in the drawings as,being made of metal, I have found that other types of material such as leather and cardboard paper may be used to advantage, and in some instances is even more advantageous. The forming ring may be secured to the curved expander strip 10 in any suitable manner. In the case of a metal ring, a few spot welds will'suffice. When using leather or cardboard paper, I have found it entirely practical to use Staples. As before stated, the ring member 13 is used to acc'urately position the strip member 10 relative to the packing flange. Once in place relative to the packing fiange, a'heavy pressure plate member is clamped tightly against the ring and expander strip and the expander strip is therefore tightly clamped in place relative to the packing flange. Therefore, the means used to secure the ring and expander strip together need be only of a temporary nature capable of holding the expander stripl correctly formed until it is clamped in place by the pressure plate.

In the Figures 12, 13 and 14, I illustrate the preferred embodiment of my invention as used with a piston cup type fiange packing. In these illustrations, the reference character refers to a cylinder Wall, the reference character 31 refers to a piston, and the reference character 32 refers to a pressure plate member held in place by a suitable bolt 33. A commonly used cup type flange packing, in this instance a full diameter cup type fiange packing 34, is illustrated. The packin: 34 has a disc portion 35 and a flange portion 36.

In the Figure 12, the embodiment of my invention illustrated by the Figures 6 and 7, is employed. In the use of this embodiment of my invention, the packing 34 is pressed into place into the cylinder 30 with the disc portion 35 tightly.

against the face of the piston 31. My improved expander device as illustrated in the Figures 6 q 4and 7 is then pressed into place as illustrated inthe Figure 12 With the pressure wall portion 16 thereof tightly pressing against the flange portion 36 of the packing 34. The pressure wall portion 16 of the expander device 10, it Will be noted, tends to extend out further than the available room provided, and Will therefore be flexed downwardly toward the pressure plate 32. Therefore, the expander member is ready to serve its purpose by forcing outwardly against the fiange 36 and -hold the flange 33 tightly against the wall of the- The pressure plate 32 is then placed cylinder 30. in contact With the ring 13 and held firmly thereagainst by means of the bolt 33. Therefore, the expander device and ring 13 are held against dislodgment by rapid changes of direction during the operation of the piston 31. The expander device 10 and the ring 13 need no positive placement guide relative to the flange 36, because the ring 13 is provided in the proper dianieteryand therefore Will accurately position itself relative to the flange 36.

In the Figure 13, I have illustrated' a notch 31- in the flange 33 in order to more firmly position the expander device 10 and the ring 13 in place.

In the Figure 14, I have illustrated the use of my improved expander device 10 Without the forming ring 13. In this embodiment, the expander strip 13 may be shipped to the point of use in straight strips, or may be flexed into the arcuate condition and the ends thereof looked.

together. In the use of this expander strip 10 without the forming ring 13, the pressure plate 32 is provided with a narrow notch 38 having a backtwall 39 accurately spaced from the inner surface of the fiange 38. Thus, the expander strip 10 may be flexed into its arctuate shape, and positioned With the bottom land portion 11 thereof in contact with the surface of the pressure plate 32 between the notch 38 and the outer circumference of the pressure plate 32, and with the anchor Wall portion 15 thereof disposed Within the notch 38 and against the accurately positioned back Walls 33 of the notch 33. Therefore, the pressure Wall portion 15 of the expander device 10 will be accurately positioned relative to the inner surface of the fiange 33, and Will provide even pressure completely around the inner surface of the packing flange 36. t

I In the Figure 15, I have illustrated a modification of my preferred embodiment expander for use With a fiange packing having only a circular sealing leg rather than a disc member as illustratedkr in the previous figures. In this embodiment, a notch 41 is provided in the pressure plate 32, and the strip expander is provided Withvan upwardly extending anchor leg 42 in place Iof the downwardly depending leg or anchor wall 15. It will be readily apparent,that the leg 42 will provide substantially the same flexibility in the expander device as provided byl the depending legs itbecauseit. is. positioned at an angle to the plana. :or iiexing. This: embodiment of my' expander device is .accurately positioned relative to the inner surface of the fiange B by a baclf: Wall Moi' the notch ti, against which the anchor leg 42." abuts, In. all other respect-s, this embodiment of my improved expander deviceoperates similar tov the embodiment illustratc-d inthe, Figureslz, iii-audit.

In the Figure 16, I have shown a cross-section'al view of a.. further embodiment of my in.- vention. portion. l li is all in one 'plans and may be, inserted betweenv the pressure plate 32 and the pacling 3.4 Without the provision of a special notch. Thus, the embodiment of this invention is bent only along one of the illustrated bend lines Zl: of Figure l. This expander device will be positioned relativc vto the packing by the abutrnent .of the pressure plate 32 against the expander at the bond between the pressure Wall portion lit? and the bottom land portion iii. This embodiment is useful in larger diameter packings in which the flexibility is suiiciently provided by only one legI being at an angle to the plans of the bottom land portion ii.

In the Figures 8, 9, 10 and ll, I have illustrated a' second embodiment of improved expanderdeviceu-'hich may be used to provide outwardly extending pressure as described in connection With the embodiment of Figures Ii' and and illustrated'in use in the Figures 12, 13 and le, and in addition thereto, may be used to provide inwardly extending force and apply pressure to the surface of a shaft -sealing fiange packing when flexed in the opposite direction. In this embodiment of my invention, substantially symmetric cleavages 45 and i are provided in the expander blank. The series of cieavages 45 are rectangular slot members extending from the side edge i i ihwardly of the strip, and the series of cleavages 46 extend inwardly of the strip from the side edge |-2. lThe cleavages 46 are rectangular slot clear-- ages substantially identical to the slot cleavages 45. The strip thus provided comprises a plurality of leg members f? along the side edge 12 and a plurality of leg members i along the side edge Il. Further, this embodiment of my invention is hent along the bend lines Which are in everyl respect similar to the bend lines illustr-ated in the Figure 1, and are therefore numbered 21 and 28 as in the Figure 1. This embodiment of my invention also has substantially the same cross-sectional configuration as the first described embodiment, and is illustrated in the Figure I! oi' the drawing. However, in operation this embodiment of the invention may be fiexed -about either of two oppositely disnosed centers,

as illustrated by the Figures 9 and 10, respectively. This freedom to iiex in both directions -i-sv accomplished by the provision or slot cleavages 46 along the side edge i2 rather than the cut cleavages 22 as illustrated in the Figure l. Thus, either leg members'l or the leg members d may be brought closer together in order to flex the In this embodiment, the foundation.

the, invention may be provided either lvvith or Witliuiij,V a forming Vring as described in connection With Vthe -first embodiment of the invention. If used, the forming ring serves substantially the samepurpose and is used in the same Way.

InV the Figure 17 of the drawing, I illustrate a third; embodiment of my invention. In this embodimellz'the blank 28 is in every respect similar toV the, blank-illustrated in the Figure 1, but the bend lines. andrl thereof are positioned laterallyi closer to the side edge i2. The result of positioning; the bend lines closer to the side edge 12., is; to lehgthen the leg members 24 along'the side. edge. 12, and to shorten the leg members 23 along theside edge H. Thus, when fiexed aboutv a-v cii"cumference, the third embodiment of my inventionwill appear as'in Figures 18 and 19 with the leg members 2% adapted to press inwardly of the4 circumference, and may be used to force a shaft sealtightly against a shaft. This embodiment of. my invention may be provided With a iorming. ring, or may be used by providing a positionihg groove. Further, it may be provided with aneupturned anchor portion. These variations are similar to the Variations described in connection With the rst embodiment illustrated inthe Figures 1 through 7.

The Fi'gllr'es 21 through 24 are cross-sectional views :through a shaft packing gland employing expander devices made in -accordance With the principles of this invention. In the Figure 21, aforming ring 52 is provided, and a pressure plail 53 tightly contacts the ring 52 and holds the expander device in fixed relationship to a shaft flange packing 54. V V

In jthe Figure 22 ofthe drawings, thesame typepacking With a forming ring -52 is employed,y but the pressure plate 53 is provided with a recess notch 55 to accommodate the expander andl ring. In this view, I have illustrated the packing 54 as eXtend-ing beyond the notch E15V to provide additional seal.

In the Figure 23, I have illustrated a condition similarV to the illustration Figure lll. That is, a notch 56 is provided in the pressure plate, 53 and has a back Wall 5.1 against Which the anchor portion of the expander device may abut. and thus be accurately spaced relative to the packing.

The-Figure 24 illustrates the third embodiment of the-invention having an upturned anchor portion 58. This embodiment is similar in crosssectional configuration to the embodiment illustratedin the Figure 15, but differs in'relationship .of parts as described, because of the shited bend lines making the leg members 2,4 longer than the. leg members 23, and being adapted to flex about .a center .opposite to the center about Which the expander device of Figure 15 is flexed. As statedin conjunction With the embodiment illustratedin .theFigure 1.5, the end portion -523 is aty .anangle to the bottom land portion ofthe expander, andV therefore the expander is free to flex about .the .circumference As described in this disclosure and claimed in theappended claimS, my invention comprises the method of iproducing flexibility ina strip ex.-

pander member. The first embodiment provides amaximum .of packingcontact area in a cylinder type packing, and the third embodiment provides a maximum of contact area in a hat type or shaft packing. The second embodiment is universally flexible and serviceable for either type of packing. Also, the expander strip has proven successful for other uses than packing expanderaI as described. For example, I have found that the blank 20 maybe bent along slightly different bend lines to produce a useful backing for an oil wiper on the tool carriageways of a machine tool such as a lathe. Also, the strip may be used as a Weather strip, or a weather strip backing and Will flex to tightly contact the window edge, regardless of irregularities in the edge.

Although I have described my invention Wit a certain degree of particularity in its preferred form,iit is understood that the present disclosure of the preferred form has been made only by Way of example and that numerouschanges in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

l. A packing expander comprising, a universally flexible strip of spring metal resistant to flexing deformation, said expander having a crosssectional configuration including a foundation portion With an anchor leg, said foundation portion having a width greater than the length of said anchor leg and lying in a predetermined plane, and a pressure-exerting Wall legw portion, said pressure-exerting Wall consisting of a series of separate sections formed from a solid strip by division cuts with no material removed between the sections and Which lie together When the strip is extended in a straight line to form a Wall with substantially no space between the sections, said anchor leg and pressure-exerting wall extendingV from said foundation portion in diverging paths, the division cuts between the sections constituting a first series of cleavages extending transversely of said expander, a second series of cleavages in the form of slots extending across the anchor leg and foundationrportion, said first and second series of cleavages being longitudinally staggered to retain said expander as a onepiece structure.

2. A packing expander comprising, a plurality of separate pressure-exerting blades laterally disposed into a composite longitudinal Wall, each blade having two cross-arm members extending therefrom, and an anchor leg portion joining cross-arm members of adjacent blades, one of said cross-arm members of each blade extending to the anchor leg portion joining that cross-armimember with a cross-arm member of a first adjacent blade, and the other cross-arm member extending to the anchor leg portion joining that other member With a cross-arm number of a second adjacent blade, said crossarm members being spaced one from the other, said expander having a, cross-sectional configuration which is generally U shaped With the blades forming one leg and the anchor leg portion forming the other leg of the U, said leg portion formed of the blades being substantially longer than said anchor leg portion, and in which the blades and the anchor leg portion extend in generally diverging paths.

3. A packing expander comprising, a universally flexible strip of spring metal resistant to s of the U and the anchor leg and pressure-exerting wall forming the legs thereof, said pressure-exerting wall being substantially longer than said anchor leg portion, said anchor leg and wall leg extending in generally diverging paths, said expander-having a first series of cleavages, each cleavage of the first series extending transversely of said article at least across said foundation portion, said expander having a second seriesof cleavages, each cleavage of the second series extending transversely of said expander at least across said foundation portion, said first and second series of cleavages being longitudinally staggered to retain said expander as a one-piece structure, at least one of said series of cleavages being in the form of longitudinal slots.

4. A packing expander comprising, a universally flexible strip of spring metal resistant to flexing deformation, said expander having a cross-sectional configuration including a foundation portion With an anchor leg, and a pressure-exerting wall leg portion, said cross-sectional configuration being generally lU-shaped With the foundation portion forming the bottom of the U and the anchor leg and pressure-exerting Wall forming the legs thereof, said anchor leg and wall leg extending from said foundation portion in generally diverging paths, said pressure-exerting wall portion being substantially longer than said anchor leg portion, said expander having a first series of cleavages, each cleavage of the first series extending transversely of said article at least across said foundation portion, said expander having a second series f of cleavages, each cleavage of the second series extending transversely of said expander at least across said foundation portion, said first and second series of cleavages being longitudinally staggered to retain said expander as a one-piece structure, both said series of cleavages being in the form of longitudinal slots.

5. A packing expander comprising, a universally flexible strip of spring metal resistant to flexing deformation, said expander having a cross-sectional configuration including a foundation portion with an anchor leg, and a pressureexerting wall leg portion, said cross-sectional configuration being generally U-shaped with the foundation portion forming the bottom of the U and the anchor leg and pressure-exerting wall forming the legs thereof, said anchor leg and Wall leg extending in generally diverging paths, said expander having a first series of cleavages, each cleavage of the first series extending transversely of said article at least across said foundation portion, said expander having a second series of cleavages, each cleavage of the second series extending transversely of said expander at least across said foundation portion, said first and second series of cleavages being longitudinally staggered to retain said expander as a one-piece structure, one Yof said series of cleavages being in the form of longitudinal slots, the other series of cleavages being in the form of simple division cuts.

6. A packing expander comprising, a universally flexible strip of spring metal resistant to flexing deformation, said expander having a crosssectional configuration including a foundation portion with an anchor leg, and a pressure-exerting wall leg portion, said cross-sectional configuration being generally U-shaped 'With the foundation portion forming the bottom of the U and the anchor leg and pressure-exerting wall forming the legs thereof, said anchor leg and Wall leg extendin'g in generally diyerging paths, said pressure-exerting wall portion ibeing substantially longer than said anchor leg portion, said exi pander having a first series of cleavagesgeach longitudinally staggered to retain said expander as a one-piece structure, at least one of said series of cleavages'being in Vthe form of longitudinal slots, and'a forming ring, said expander being flexed to conform to the shape of said forming ring, said forming ring and expander fitting together lWith the ring united to the foun'dation portion of the expander.

ALDRICH R. kHIilDB'IElltG.

12 REFERENCES GIT-ED- 'The *following references are of record in the le of this'patent: I

IU1\II'T'ED STATES PATENTS Number NameV Date 345,76? 'Buckley July 20, 1886 1,316g534 Cox Sept. 16, 1919 1,938,249 Fretter Dec.V 5, 1933 1,958,120 Tuxbury et al V May 8, 1934 1,969,'0O8 VHubbard Aug. '7, 1934 '2,049;'063 Hubbard July 28, 1936V 2,088270'3 Hubbard et al Aug. 3, 1937 '2224,33'8 'Bowers Dec. 10, 1940 '2.342,458 LDavies Feb. 22, 19441 F2,434,48'4 Chambers Jan. 13, 1948 "'2,434,485 Chambers Jan. 13, 1948 

